Print hammer striking moving type at an angle to compensate for frictional force

ABSTRACT

A printing device comprising a type support and one or more hammers cooperating therewith. Each hammer has an impact beam which is arranged so that it strikes the face of the type support at an angle in such manner that the reaction force exerted on the impact beam during a stroke of the impact beam against said face has a component, in addition to a component in the direction of the impact beam equal to the frictional force exerted on the impact beam.

United States Patent Quirijnen Sept. 18, 1973 [75] Inventor: Marius Qnlrijnen,Rijswijk,

Netherlands [73] Assignee: U.S. Philips Corporation, New York,

[22] Filed: May 21, 1971 [211 App]. No.: 145,692

[30] Foreign Application Priority Data June 4, 1970 Netherlands 7008102 [52] U.S. Cl 101/93 C [51.] int. Cl B41j 9/02 [58] Field of Search. l0l/93 (3,111,110

[56] References Cited UNITED STATES PATENTS 3,128,694 4/1904 Kittler 101/93 C L I I H1966 l2/l966 3/l967 ll/l967 ll/l97l Miller l0l/93 C Mutz Solheim et al.

Sariti l0l/93 C Buehrmann et al. l0l/l ll X Primary Examiner-Robert E. Pulfrey Assistant Examiner-15. M. Coven Attorney-Frank R. Trifari [57] ABSTRACT A printing device comprising a type support and one or more hammers cooperating therewith. Each hammer has an impact beam which is arranged so that it strikes the face of the type support at an angle in such manner that the reaction force exerted on the impact beam during a stroke of the impact beam against said face has a component, in addition to a component in thedirection of the impact beam equal to the frictional force exerted on the impact beam.

3 Claims, 4 Drawing Figures PATENIEDSEHMBH 3.759. 1 74 suzcnnrz i/ I s 2 l I lw -3 4- Fig.1

Fig.2

INVENTOR. MARIUS QUIR'JNEN PATENTEB $5? I 8 73 Fig.4

INVENTOR. MARIUS QUIR JNEN PRINT HAMMER STRIKING MOVING TYPE AT AN ANGLE TO COMPENSATE FOR FRICTIONAL FORCE The invention relates to a printing device comprising a type support and one or more hammers cooperating therewith and each comprising an impact beam.

Printing devices of the above-described type are known and the hammers in these devices are driven mechanically, electromagnetically or electrodynamically. It is generally required that the time of movement and contact of the impact beam be as short as possible and remain constant so as to obtain a high stroke frequency and a truly uniform reproduction of the characters to be printed. In order to satisfy the said requirement, the impact beam must be resistant to detrition and be rigid and furthermore the mass of the impact hammer must be as small as possible. The hammers are often arranged on supporting members which may be in the form of leaf springs.

A drawback of these known printing devices is that the impact beam of each of the hammers is arranged so that the face of the type support is hit at an angle of 90. When the impact beam strikes against the type support, first of all the reaction force of the stroke with which the impact beam strikes against the type support acts on the impact beam, while furthermore a frictional force is exerted on the impact beam due to the continuously moving type support and the paper which is taken along in a slipping manner during the stroke. As a result of this frictional force rather large stresses occur in the supporting members of the impact beams which considerably reduce the life of said members.

It is the object of the invention to avoid this drawback and to provide a printing device in which the-frictional force exerted on the impact beam is compensated for by a component of the reaction force exerted on the impact beam.

In order to realize this object, the printing device according to the invention is characterized in that the impact beam of each of the hammers is arranged so that it strikes against the face of the type support at an angle such that the reaction force exerted on the impact beamduring the stroke of the impact beam against said face has a component, in addition'to a component in the direction of the impact beam, which is directed opposite to and is substantially equal to the frictional force exerted on the impact beam.

Since in the printing device according to the invention the impact beam of each of the hammers is arranged so that the face of the type support is struck at such an angle that the reaction force has a component which compensates for the frictional force, the supporting members of said impact beams are now no longer exposed to large stresses so that the life of the printing device is considerably improved. Furthermore, the quality of the printed characters is considerably improved.

In a further favorable embodiment of the printing device according to the invention, in which the type support is conctructed as a type roller, the impact beam of each of the hammers, viewed in the direction of rotation of the type roller, is arranged in front of the plane passing through the axis of the type roller and parallel to the impact beam. By the use of this construction the reaction force exerted on the impact beam during the stroke has a component which is opposite to the frictional force and can compensate for said force.

In a further favorable embodiment of the printing device according to the invention, in which the types are supported by a chain or band, the impact beam of each of the hammers encloses an acute angle with the part of the chain and band, respectively, which, viewed in the direction of movement of the chain and band, respectively, is located after the relevant impact beam.

In order that the invention may be readily carried into effect, it will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which FIG. 1 shows diagrammatically and not to scale a known printing device having a type roller FIG. 2 shows diagrammatically a printing device having a type roller in which the impact beam strikes the face of the type roller at an acute angle,

FIG. 3 shows diagrammatically and not to scale a printing device having a type roller in which the impact beam of the hammer, viewed in the direction of rotation of the type roller, is arranged in front of the plane passing through the axis of the type roller and parallel to the impact beam,

FIG. 4 shows diagrammatically a printing device in which the types are supported by a chain and in which the impact beam encloses an acute angle with the part of the chain which, viewed in the direction of movement, is located after the relevant impact beam.

Referring now to FIG. 1, reference numeral 1 de notes a type roller which rotates in the direction denoted by an arrow. Opposite to the type roller 1 an impact beam 2 is arranged which is secured to a supporting block 5 by supporting members 3 and 4, in the form of leaf springs. The printing paper 6 is present between the-type roller 1 and the impact beam 2. The type roller 1 moves continuously. In this known printing device the impact beam 2 is arranged at the level of the axis 7 of the type roller 1. During a stroke of the impact beam 2, which is driven in a manner not shown, the impact beam strikes the paper 6 and the type roller 1 at an angle of and the reaction force S caused by the stroke with which the impact beam 2 strikes against the type roller 1, and a frictional force W caused by the movement of the type roller act upon the impact beam 2. This frictional force W causes rather large stresses in the supporting members 3 and 4, which stresses considerably reduce the life of said supporting members, which, naturally, is disadvantageous while as a result of this the printing quality is also adversely influenced.

FIG. Zshows a printing device which generally corresponds to the device shown in FIG. 1 and the components of which are denoted by the same reference numerals. In this device, however, the impact beam 2 is arranged so that its direction corresponds to th direction of the resultant of the forces S and W of FIG. I. The result of this is that, during a stroke of the impact beam 2 against the type roller 1, the reaction force S, which of course is again directed at right angles to the surface of the type roller, now has, in addition to a component S, in the direction of the impact beam, a component S, which is directed opposite to and is equally large as the frictional force W. The adverse influences of the frictional force W on the life and the printing quality have thus been fully eliminated.

FIG. 3 shows diagrammatically a printing device which generally corresponds to the device shown in the preceding Figures and the components of which are therefore referred to by the same reference numerals.

In the device shown in FIG. 3, the impact beam 2 is displaced against the direction of rotation of the roller 1 so that the impact beam 2 is now arranged in front of the plane passing through the axis 7 of the roller 1 and parallel to the impact beam. The result of this is that the reaction force S which acts upon the impact beam is now resolved into a reaction force S, in the direction of the impact beam and reaction force S, in a direction at right angles thereto and directed upwards. So this reaction force S acts in a direction opposite to the frictional force W so that said forces can compensate for each other in the case of suitable choice of the arrangement of the impact beam. Since the forces S and W compensate for each other, the supporting members 3 and 4 are no longer loaded in their longitudinal directions by the said forces so that no large stresses can occur in the said supporting members any longer and their lifetime is considerably improved. All this is achieved without the introduction of extra structural components. Direction of rotation of the type roller in the construction of the printing device shown in FIG. 2 is to the right, the impact beam 2 in this case is present above the axis of the type roller. If on the contrary it deals with a type roller the direction of rotation of which is to the left, the impact beam 2 should be arranged below the axis of. the type roller 1.

FIG. 4 shows a printing device in which the types are supported by a chain 8 which is moved in the direction of the arrow in a manner not shown. The impact beam 9 is arranged so as to enclose an acute angle a with the plane of the chain. By this arrangement it is achieved that the reaction force S which acts upon the impact beam 9 during a stroke, has a component S in the direction of the impact beam and a component S which is directed opposite to and is substantially equally large as the frictional force W acting upon the impact beam. So in this construction also the frictional force has been compensated for.

It will be clear'from the above that the invention provides a printing device in which the frictional force is compensated for in a surprisingly simple manner and without the introduction of extra structural components, as a result of which a longer life and a better printing quality is obtained than in the known printing devices.

Although in the above embodiments leaf springs have been used by way of example as supporting members for the impact beams, it will be obvious that in the case of other guides for said impact beams the advantages of the arrangement of the impact beam according to the invention occur to the same extent.

I claim:

1. A printing device comprising a continuously moving type support and at least one print hammer arranged for cooperation therewith, said print hammer comprising a base member, a rigid impact beam arranged for movement toward and away from said type support, one end of said impact beam forming an impact surface for engagement with said type support, thereby producing a frictional force on said impact beam at the moment of engagement and a reaction force, and support members carried by said base for supporting said impact beam so that upon movement thereof into engagement with said type support said impact beam will strike said type support at an angle so that said reaction force has a first component in the direction of said impact beam, and a second component being substantially equal and opposite to said frictional force.

2. The printing device according to claim 1 wherein said type support is a rotating type roller having printing characters on the surface thereof, and wherein said impact beam is supported by said support members in front of the plane passing through the axis of said type roller and parallel to said impact beam.

3. The printing device according to claim 1 wherein said type support is a continuously moving endless band, and wherein said impact beam is supported to form an acute angle with the part of said band which has passed said impact beam. 

1. A printing device comprising a continuously moving type support and at least one print hammer arranged for cooperation therewith, said print hammer comprising a base member, a rigid impact beam arranged for movement toward and away from said type support, one end of said impact beam forming an impact surface for engagement with said type support, thereby producing a frictional force on said impact beam at the moment of engagement and a reaction force, and support members carried by said base for supporting said impact beam so that upon movement thereof into engagement with said type support said impact beam will strike said type support at an angle so that said reaction force has a first component in the direction of said impact beam, and a second component being substantially equal and opposite to said frictional force.
 2. The printing device according to claim 1 wherein said type support is a rotating type roller having printing characters on the surface thereof, and wherein said impact beam is supported by said support members in front of the plane passing through the axis of said type roller and parallel to said impact beam.
 3. The printing device according to claim 1 wherein said type support is a continuously moving endless band, and wherein said impact beam is supported to form an acute angle with the part of said band which has passed said impact beam. 